The present invention relates generally to a system for monitoring tire pressure in an automotive vehicle, and more particularly, to a method and system for automatically including auxiliary tires such as for trailers and additional spare tires.
Various types of pressure sensing systems for monitoring the pressure within the tires of an automotive vehicle have been proposed. Such systems generate a pressure signal using an electromagnetic (EM) signal, which is transmitted to a receiver. The pressure signal corresponds to the pressure within the tire. When the tire pressure drops below a predetermined pressure, an indicator is used to signal the vehicle operator of the low pressure.
Various tire manufacturers have suggested various locations for the pressure sensors. Known systems include coupling a pressure sensor to the valve stem of the tire. Other known systems and proposed systems locate the pressure sensors in various locations within the tire wall or tread.
Sport utility vehicles and other large vehicles are often used to pull a trailer. It is desirable to monitor the condition of the trailer tires as well as the primary vehicle tires. U.S. Pat. No. 6,225,895 describes a system in which the condition tires to a trailer are monitored using a mechanical linkage therebetween. The system visually monitors the conditions of the tires and does not directly measure pressure loss.
U.S. Pat. No. 5,061,917 measures various parameters and transmits them to the cab of the tractor trailer unit. The transmitter to this system only transmits when a fault occurs. Also, a bank of switches is used to provide the position of each tire on the vehicle before operating.
One problem with the above systems is that driver Intervention is required to properly configure the system. Another drawback is that sensors from adjacent vehicles may also be read as belonging to the vehicle monitoring system.
Also, the trailer or the top of the vehicle may also be used to store additional spare tires when more than one spare tire is desirable. Such conditions such as an off-road condition far from most civilization require having more than one spare. Additional spare tires are typically not provided for in tire monitoring systems. It would therefore be desirable to provide a system in which spare tires and trailer tires are monitored.